title: Prevalence and characterisation of plasmid-mediated quinolone resistance and mutations in the gyrase and topoisomerase IV genes among Shigella isolates from Henan, China, between 2001 and 2008.
abstract: A total of 293 Shigella isolates were isolated from patients with diarrhoea in four villages of Henan, China. This study investigated the prevalence of the plasmid-mediated quinolone resistance (PMQR) genes qnrA, qnrB, qnrS, qepA and aac(6')-Ib-cr and compared the polymorphic quinolone resistance-determining regions (QRDRs) of gyrA, gyrB, parC and parE. Of the isolates, 292 were found to be resistant to nalidixic acid and pipemidic acid, whereas 77 were resistant to ciprofloxacin (resistance rate of 26.3%). Resistance of the Shigella isolates to ciprofloxacin significantly increased from 2001 to 2008 (P<0.05). A mutation in gyrA was present in 277 (94.5%) of the isolates and a mutation in parC was present in 19 (6.5%) of the isolates. Moreover, 168 (57.3%) of the isolates contained only the gyrA (Ser83Leu) mutation. In addition, 107 isolates had two gyrA point mutations (Ser83Leu and either Asp87Gly, Asp87Asn or Asp113Tyr) and 13 isolates had two gyrA point mutations (Ser83Leu and Asp87Gly or Gly214Ala) and one parC mutation (Ser80Ile). In addition, qepA and aac(6')-Ib-cr were present in 6 (2.05%) and 19 (6.48%) of the isolates, respectively. All but one of the PMQR-positive isolates with a ciprofloxacin minimum inhibitory concentration in the range 4-32μg/mL had a mutation in the QRDR. It is known that PMQR-positive Shigella isolates are common in China. This study found that there was a significant increase in mutation rates of the QRDR and the resistant rates to ciprofloxacin. Other mechanisms may be present in the isolates that also contribute to their resistance to ciprofloxacin.
authors.affiliation: Department of Epidemiology, College of Public Health, Zhengzhou University, No. 100 Science Road, Zhengzhou, Henan, People's Republic of China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Yang
authors.forename: Guangcai
authors.initials: G
authors.lastname: Duan
authors.forename: Jingyuan
authors.initials: J
authors.lastname: Zhu
authors.forename: Weidong
authors.initials: W
authors.lastname: Zhang
authors.forename: Yuanlin
authors.initials: Y
authors.lastname: Xi
authors.forename: Qingtang
authors.initials: Q
authors.lastname: Fan
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002681:China; D027081:DNA Gyrase / Q000235:genetics*; D027101:DNA Topoisomerase IV / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D004405:Dysentery, Bacillary / Q000382:microbiology; D005798:Genes, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D010957:Plasmids; D015363:Quinolones / Q000494:pharmacology*; D017422:Sequence Analysis, DNA; D012760:Shigella / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D015363:Quinolones; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase
keywords: China; Ciprofloxacin; PMQR; QRDR; Shigella